The invention provides planar lateral FET structure for bidirectional power switching, including AC application. The invention particularly provides enhanced OFF state voltage blocking capability in a planar device by means of field shaping in the drift region to straighten out field lines and prevent curvature crowding in the drift region portion between the channels. This prevents gradient induced depletion and unwanted inversion of conductivity type along the drift region portion between the channels during the OFF state. As a result, for a given ON state resistance specification, a greater blocking voltage can be obtained; or conversely, for a fixed OFF state blocking voltage requirement, a lower ON state resistance can be obtained.
Copending Application Ser. No. 390,562, filed June 21, 1982 discloses planar lateral AC power FET integrated structure. Copending Application Ser. No. 421,931, filed Sept. 23, 1982 discloses nonplanar AC power FET structure with current flow along the sides of a vertical notch, with a field shaping region forming a junction with the drift region opposite the channel-containing region junctions.